scholarly journals Nest caging as a conservation tool for threatened songbirds

2014 ◽  
Vol 41 (7) ◽  
pp. 598 ◽  
Author(s):  
Richard E. Major ◽  
Michael B. Ashcroft ◽  
Adrian Davis
Keyword(s):  
Reproductive Success ◽  
Nest Success ◽  
Nesting Success ◽  
Wire Mesh ◽  
Management Tool ◽  
Negative Effects ◽  
Artificial Nests ◽  
Endangered Population ◽  
Precocial Birds ◽  
Nest Predators

Context Enclosing nests in cages to exclude predators is a management tool frequently used to increase the reproductive success of threatened ground-nesting precocial birds. This technique has seldom been used with passerines, despite the predicted increased benefit for altricial species due to their longer period of nest dependency. Aims The aims of this study were to determine (1) whether cages could be installed around the nests of a threatened, shrub-nesting passerine without causing parental desertion, and (2) whether caged nests could successfully exclude the dominant nest predators and increase nesting success. Methods Cages with four different mesh sizes (1000 mm, 200 mm, 100 mm, 50 mm) were installed sequentially in trials at four nests in a secure population and three nests in an endangered population of white-fronted chats (Epthianura albifrons) to investigate susceptibility to desertion. Trials using 160 caged and uncaged artificial nests were used to determine the efficacy of 50-mm wire mesh in preventing access to eggs by potential nest predators. Key results Parent birds accepted nest cages, which reduced predation rates on artificial nests from 96% to 14%. Infrared-triggered cameras revealed that corvids were responsible for 94% of predation episodes. Nest success of caged white-fronted chat nests was 85% (n = 7). Conclusions Nest cages do not appear to have negative effects on nest success of white-fronted chats, and may considerably increase reproductive success. Implications Nest cages may aid conservation of the endangered population of white-fronted chats and other endangered songbird species.

scholarly journals Evaluating the ecological and behavioural factors influencing Snowy PloverCharadrius nivosusegg hatching and the potential benefits of predator exclosures

2014 ◽  
Vol 26 (1) ◽  
pp. 100-118 ◽  
Author(s):  
SCOTT F. PEARSON ◽  
SHANNON M. KNAPP ◽  
CYNDIE SUNDSTROM
Keyword(s):  
Spatial Scales ◽  
Nest Success ◽  
High Tide ◽  
Quadratic Function ◽  
Wire Mesh ◽  
Habitat Characteristics ◽  
Conservation Strategies ◽  
Active Nest ◽  
Factors Influencing ◽  
Nest Predators

SummaryAn understanding of the ecological factors influencing nest success and the effectiveness of management activities focused on improving nest success can be critical to successful conservation strategies for rare or declining species. Over seven breeding seasons (2006–2012) we examined the influence of nest spacing and habitat characteristics on hatching success for the nationally threatened Pacific coast population of the Snowy PloverCharadrius nivosusin coastal Washington, USA in two study areas. Specifically, we assessed the influence of clutch age, nesting season date, distance to conspecific nests, perpendicular distance to the high-tide (wrack) line, vegetation cover and other habitat characteristics at three spatial scales (1m2, 5m2, and 25 m2) centred on the nest. We also assessed the effectiveness of wire mesh cages placed around nests to exclude mammalian and avian nest-predators. We discovered and monitored 307 nests, placed predator exclosures around 142 of these nests and measured habitat variables at 251. Our selected base model included site and quadratic function of season-date. For the analysis examining habitat effects on nest success, only models with distance to nearest active nest ranked higher than the baseline model even when removing the nests that were very distant from conspecific nests (outliers). For these unexclosed nests, predation was the primary source of nest failure and crows and ravens were apparently the primary nest predators. Predator exclosures had a clear positive influence on nest survival. Even though we observed a positive exclosure effect, we recommend that they be used cautiously because we and others have observed adult mortality associated with exclosures. Regardless of the spatial scale, Snowy Plovers are primarily using nest sites with little vegetation, shell or woody material cover suggesting the need for large expanses of very sparsely or unvegetated habitats that allow birds to nest semi-colonially (with near neighbours).

scholarly journals Nesting Success and Nest Predators in Forest Fragments: A Study Using Real and Artificial Nests

The Auk ◽  
2000 ◽  
Vol 117 (2) ◽  
pp. 445-454 ◽  
Author(s):  
Liana Zanette ◽  
Bert Jenkins
Keyword(s):  
Nest Predation ◽  
Agricultural Land ◽  
Fragment Size ◽  
Nesting Success ◽  
Forest Fragments ◽  
Artificial Nests ◽  
Area Sensitivity ◽  
Avian Nest ◽  
Nest Predator ◽  
Nest Predators

Abstract Area sensitivity in songbirds is commonly attributed to increased nest predation in forest fragments. In 1995 and 1996, we tested whether the nest predators and nesting success of an area-sensitive forest bird, the Eastern Yellow Robin (Eopsaltria australis), varied with fragment size, and we also conducted an artificial nest experiment. The study occurred in two small (55 ha) and two large (>400 ha) forest fragments in a matrix of agricultural land in New South Wales, Australia. Predation accounted for 95% of all failures of 282 robin nests, and the survival of robin nests was negatively correlated with how frequently we observed avian nest predators near nests (i.e. nest-predator activity). Of 461 artificial nests, 84% were depredated, nearly all (99%) by birds. Thus, birds were important predators of nests. The abundance, species richness, and activity of avian nest predators were not related to fragment size. Survival of robin nests averaged 19%; nests in small fragments had a 22% chance of producing at least one fledgling compared with 15% in large fragments, but the difference was not significant. Survival of artificial nests averaged 12% in both small and large fragments. Nest-predator activity accounted for the most variation (68%) in the fate of robin nests, followed by the cumulative density of open-cup nesters (16%). The placement of robin nests had no influence on nest fate. We conclude that nest predation was not area dependent and propose food supply as an alternative hypothesis to explain area sensitivity. We suggest that, rather than being related to fragment size, nest predation increases with decreasing forest cover in a landscape. Increased nest predation in fragmented compared with contiguous landscapes may lower the population viability of songbirds in a region, and hence regional numbers. Therefore, the spatial scale at which fragmentation influences nest predation and songbird populations must be considered carefully.

scholarly journals Conspecific and heterospecific grass litter effects on seedling emergence and growth in ragwort (Jacobaea vulgaris)

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246459
Author(s):  
Henrike Möhler ◽  
Tim Diekötter ◽  
Geeltje Marie Bauer ◽  
Tobias W. Donath
Keyword(s):  
Seedling Emergence ◽  
Management Tool ◽  
Litter Type ◽  
Negative Effects ◽  
Positive Effects ◽  
Mediated Effects ◽  
Jacobaea Vulgaris ◽  
Grass Litter ◽  
Early Seedling ◽  
Biomass Plant

Jacobaea vulgaris Gaertn. or common ragwort is a widespread noxious grassland weed that is subject to different regulation measures worldwide. Seedling emergence and growth are the most crucial stages for most plants during their life cycle. Therefore, heterospecific grass or conspecific ragwort litter as well as soil-mediated effects may be of relevance for ragwort control. Our study examines the effects of conspecific and heterospecific litter as well as ragwort conditioned soil on seedling emergence and growth. We conducted pot experiments to estimate the influence of soil conditioning (with, without ragwort), litter type (grass, ragwort, grass-ragwort-mix) and amount (200 g/m², 400 g/m²) on J. vulgaris recruitment. As response parameters, we assessed seedling number, biomass, height and number of seedling leaves. We found that 200 g/m² grass litter led to higher seedling numbers, while litter composed of J. vulgaris reduced seedling emergence. Litter amounts of 400 g/m² had negative effects on the number of seedlings regardless of the litter type. Results for biomass, plant height and leaf number showed opposing patterns to seedling numbers. Seedlings in pots treated with high litter amounts and seedlings in ragwort litter became heavier, grew higher and had more leaves. Significant effects of the soil conditioned by ragwort on seedling emergence and growth were negligible. The study confirms that the amount and composition of litter strongly affect seedling emergence and growth of J. vulgaris. Moreover, while conspecific litter and high litter amounts negatively affected early seedling development in ragwort, those seedlings that survived accumulated more biomass and got taller than seedlings grown in heterospecific or less dense litter. Therefore, ragwort litter has negative effects in ragwort germination, but positive effects in ragwort growth. Thus, leaving ragwort litter on pastures will not reduce ragwort establishment and growth and cannot be used as management tool.

Effects of a native crayfish (Orconectes virilis) on the reproductive success and nesting behavior of sunfish (Lepomis spp.)

2004 ◽  
Vol 61 (11) ◽  
pp. 2135-2143 ◽  
Author(s):  
Nathan J Dorn ◽  
Gary G Mittelbach
Keyword(s):  
Reproductive Success ◽  
Lepomis Macrochirus ◽  
Lepomis Gibbosus ◽  
Orconectes Virilis ◽  
Negative Effects ◽  
Fish Prey ◽  
Natural Lakes ◽  
Successful Reproduction ◽  
Young Of The Year ◽  
Native Crayfish

While crayfish are traditionally considered fish prey, they are capable of feeding on substrate-bound fish eggs and their introductions have been blamed for the decline in fish populations in Europe and North America. To investigate their potential effects on fish reproductive success we measured the effects of a native crayfish (Orconectes virilis) on the reproductive success of two substrate-nesting sunfish, pumpkinseed (Lepomis gibbosus) and bluegill (Lepomis macrochirus), in replicated pond experiments. Crayfish were observed feeding on eggs in both experiments. Crayfish presence delayed successful reproduction by pumpkinseeds in densely vegetated ponds, resulting in lower young-of-the-year biomass in ponds with crayfish. In the second experiment, with bluegills in less-vegetated ponds, crayfish prevented successful reproduction entirely. However, when we added crayfish-proof exclosures to the crayfish ponds late in the summer, bluegills located the crayfish-free habitat and successfully reproduced inside the exclosures (1 month after first successful reproduction in control ponds). The results of these experiments demonstrate the potential strong negative effects of crayfish on sunfish reproduction and suggest that the spatial distribution of crayfish and other egg predators may influence fish nesting behaviors and habitat choices. Further studies are needed to determine the magnitude of crayfish effects in natural lakes and ponds where sunfish and crayfish co-occur.

scholarly journals Early Infestation by Bot Flies (Philornis Seguyi) Decreases Chick Survival and Nesting Success in Chalk-Browed Mockingbirds (Mimus Saturninus)

The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 898-906 ◽  
Author(s):  
Fabián L. Rabuffetti ◽  
Juan C. Reboreda
Keyword(s):  
Reproductive Success ◽  
Nesting Success ◽  
Life History Strategies ◽  
Chick Survival ◽  
Southern Limit ◽  
Growth And Survival ◽  
Molothrus Bonariensis ◽  
Bot Fly ◽  
Time Of Breeding ◽  
Host Life

AbstractBot flies (Diptera: Muscidae: Philornis spp.) are a group of flies comprising mostly species with a Neotropical distribution. Their larvae parasitize several species of birds, living subcutaneously on altricial chicks. We investigated the effect of parasitism by bot flies (P. seguyi) on the reproductive success of Chalk-browed Mockingbirds (Mimus saturninus) in temperate grasslands near the southern limit of bot fly distributions. We analyzed seasonal variation of bot fly prevalence during three consecutive years and how the timing and intensity of bot fly infestation affected growth and survival of Chalk-browed Mockingbird nestlings. Bot fly prevalence was 58.3%, 30.7%, and 45.5% each year, and in all years, it increased with time of breeding. Most of the infested nests fledged no chicks. In these nests, chicks had a lower tarsus growth rate than in noninfested nests and died 3–4 days after parasitism. The average time from hatching of the first chick until infestation was 4.4 days. The age of the chicks at the time of infestation was associated positively with nesting success and negatively with intensity of parasitism. Bot fly parasitism also reduced the survival of Shiny Cowbird (Molothrus bonariensis) chicks present in Chalk-browed Mockingbird nests, but the presence of Shiny Cowbird chicks did not affect timing of infestation or fledging success of Chalk-browed Mockingbird chicks. Our results show that an intermediate prevalence of bot fly parasitism produces an important decrease in the reproductive success of Chalk-browed Mockingbirds and suggest that bot flies may play an important role as selective agents in the evolution of host life-history strategies.La Infestación Temprana con Larvas de Philornis seguyi Disminuye la Supervivencia de los Pichones y el Éxito de Nidificación de Mimus saturninus

scholarly journals Are Artificial Bird Nests Effective Surrogates for Estimating Predation on Real Bird Nests? A Test With Tropical Birds

The Auk ◽  
2005 ◽  
Vol 122 (3) ◽  
pp. 843-852 ◽  
Author(s):  
W. Douglas Robinson ◽  
Jennifer Nesbitt Styrsky ◽  
Jeffrey D. Brawn
Keyword(s):  
Nest Success ◽  
Tropical Species ◽  
Tropical Birds ◽  
Underlying Assumption ◽  
Artificial Nests ◽  
Nest Sites ◽  
Incubation Periods ◽  
Fourth Species ◽  
Species Specific ◽  
The Tropics

AbstractArtificial bird nests are often used in studying birds whose nests are difficult to find, such as those of many tropical species. Yet the underlying assumption that predation on artificial nests accurately estimates predation on real nests may be invalid. We compared rates at which contents of real and artificial nests were lost to predators in a Panamanian rainforest. We attempted to make artificial nests as realistic as possible by moving real, undamaged nests to species-typical nest sites in a study area where the same species were actively breeding. Characteristics of new sites for the moved nests were statistically similar to nest sites chosen by birds. We baited nests with two quail eggs and monitored them for species-specific incubation periods. Predation on real and artificial nests was dissimilar in three of four species, revealing that predation on artificial nests correlated poorly with predation on real nests. In a fourth species, artificial and real nests were lost at similar rates. The latter result may have occurred by chance, because depredated real nests rarely showed any sign of damage; whereas depredated artificial nests were torn, which suggests that real and artificial nests attracted different predators. Our results indicate that artificial nests, even when built by the species themselves and placed in realistic situations, are poor predictors of real nest success and we caution against their use in the tropics.Son los Nidos Artificiales Sustitutos Efectivos para Estimar la Depredación de Nidos Verdaderos? Una Prueba con Aves Tropicales

scholarly journals Nest Predators, Nest-Site Selection, and Nesting Success of the Dusky Flycatcher in a Managed Ponderosa Pine Forest

The Condor ◽  
2002 ◽  
Vol 104 (3) ◽  
pp. 507-517 ◽  
Author(s):  
Joseph R. Liebezeit ◽  
T. Luke George
Keyword(s):  
Site Selection ◽  
Nest Site ◽  
Nesting Success ◽  
Nest Site Selection ◽  
Potential Prey ◽  
Nest Sites ◽  
Dusky Flycatcher ◽  
Shrub Patches ◽  
Empidonax Oberholseri ◽  
Nest Predators

AbstractAmong hypotheses explaining nest-site selection, the potential-prey-site hypothesis predicts that birds place nests in areas with many potential nest sites, while the nest-concealment hypothesis predicts nest placement in sites with greater surrounding vegetation. We examined these hypotheses by comparing habitat attributes between Dusky Flycatcher (Empidonax oberholseri) nest sites and random sites, successful and unsuccessful nests, and nests depredated by birds versus mammals. Nesting success was 28% (n = 167), and predation was the most important cause of nest failure (96%) during the study (1998–2000) at our site in northeastern California. We identified 28 nest predators using surveillance cameras. Sciurid mammals were the most common predators (17 of 28, 61%), with Cooper's Hawks (Accipiter cooperii; 25%), small owls (11%), and Steller's Jays (Cyanocitta stelleri; 3%) accounting for the rest. Raptors preyed on nestlings more frequently than on eggs, while small mammals depredated nestlings and eggs in proportion to their availability. Dusky Flycatchers nested in larger shrub patches with greater shrub cover than at random sites, supporting the potential-prey-site hypothesis. Successful nests were in larger shrub patches surrounded by fewer seedlings and saplings compared to depredated nests, providing equivocal support for the potential-prey-site hypothesis. Nests depredated by birds were less concealed, located in smaller shrub patches, surrounded by fewer seedlings and saplings, and were closer to the shrub edge than nests depredated by mammals. Our results, strengthened by identification of nest predators, suggest that differences in search strategies among predators may constrain the ability of Dusky Flycatchers to optimize nest-site selection.Depredadores de Nidos, Selección de Sitios de Anidación y Éxito de Anidación de Empidonax oberholseri en un Bosque Manejado de Pino PonderosaResumen. Entre las hipótesis que explican la selección de sitios de anidación, la de “presa potencial” predice que las aves ubican sus nidos en lugares con muchos sitios de anidación, mientras que la de “ocultación del nido” predice la ubicación de nidos en sitios con mayor vegetación circundante. Nosotros examinamos estas hipótesis comparando características del hábitat entre sitios de anidación del mosquerito Empidonax oberholseri y sitios aleatorios, entre nidos exitosos y no exitosos, y entre nidos depredados por aves y por mamíferos. Entre 1998 y 2000 en un área del noreste de California, el éxito de anidación fue del 28% (n = 167) y la depredación fue la causa más importante del fracaso de los nidos (96%). Identificamos 28 depredadores de nidos utilizando cámaras. Los mamíferos sciúridos fueron los depredadores más comunes (17 de 28, 61%), mientras que los demás nidos fueron depredados por Accipter cooperii (25%), búhos pequeños (11%) y Cyanocitta stelleri (3%). Las aves rapaces se alimentaron con mayor frecuencia de pichones que de huevos, mientras que los mamíferos pequeños depredaron pichones y huevos en proporción a su disponibilidad. Los mosqueritos anidaron en parches con mayor cobertura de arbustos que sitios aleatorios, lo cual apoya la hipótesis de presa potencial. Los nidos exitosos se ubicaron en parches de arbustos más grandes rodeados por menos plántulas y renovales en comparación con los nidos depredados, lo que apoya equívocamente la hipótesis de presa potencial. Los nidos depredados por aves estuvieron menos ocultos, ubicados en parches de arbustos más pequeños, rodeados por menos plántulas y renovales, y estuvieron más cerca del borde del matorral que los nidos depredados por mamíferos. Nuestros resultados, fortalecidos por la identificación de los depredadores, sugieren que las diferencias en las estrategias de búsqueda entre depredadores pueden limitar la habilidad de los mosqueritos para optimizar la selección de sitios de anidación.

scholarly journals The onset in spring and the end in autumn of the thermal and vegetative growing season affect calving time and reproductive success in reindeer

2019 ◽  
Vol 66 (2) ◽  
pp. 123-134 ◽  
Author(s):  
Amélie Paoli ◽  
Robert B Weladji ◽  
Øystein Holand ◽  
Jouko Kumpula
Keyword(s):  
Reproductive Success ◽  
Time Lag ◽  
Growing Season ◽  
Plant Phenology ◽  
Negative Effects ◽  
Main Hypothesis ◽  
Vegetation Growth ◽  
Growing Seasons ◽  
Finnish Lapland ◽  
Reindeer Population

Abstract A developing trophic mismatch between the peak of energy demands by reproducing animals and the peak of forage availability has caused many species’ reproductive success to decrease. The match–mismatch hypothesis (MMH) is an appealing concept that can be used to assess such fitness consequences. However, concerns have been raised on applying the MMH on capital breeders such as reindeer because the reliance on maternal capita rather than dietary income may mitigate negative effects of changing phenologies. Using a long-term dataset of reindeer calving dates recorded since 1970 in a semidomesticated reindeer population in Finnish Lapland and proxies of plant phenology; we tested the main hypothesis that the time lag between calving date and the plant phenology in autumn when females store nutrient reserves to finance reproduction would lead to consequences on reproductive success, as the time lag with spring conditions would. As predicted, the reproductive success of females of the Kutuharju reindeer population was affected by both the onset of spring green-up and vegetative senescence in autumn as calves were born heavier and with a higher first-summer survival when the onset of the vegetation growth was earlier and the end of the thermal growing season the previous year was earlier as well. Our results demonstrated that longer plant growing seasons might be detrimental to reindeer’s reproductive success if a later end is accompanied by a reduced abundance of mushrooms.

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